Astrogeobiology

This course is merely a way to think about living things in their astronomical or cosmic context, to address questions such as the origin of life or the existence of life elsewhere that requires linking biology and geology with other fields such as planetary sciences or astronomy. This course provides a comprehensive overview of some of the major strands of science that underpin the study of life in its cosmic context, hopefully achieving an appropriate depth of understanding in key subjects such as physics, biology, chemistry and geology. Students learn about possible contamination of ancient sedimentary and extraterrestrial samples and extraction techniques of organic matter. They also examine samples collected from cold and hot deserts (examination includes microscopic analyses, isolation and cultivation of microorganisms), analyse cultured cyanobacteria, other bacteria and fungi under epifluorescence microscope; perform experiments with extremophilic taxa of cyanobacteria.

Lecture, 30h

Course comprises:

1. A brief history of astrogeobiology

2. What is life? Understanding some of the key characteristics of life is essential for astrogeobiology.

- historical perspective

- spontaneous generation

- modern concepts

3. Matter and life (the concept of atoms, ions, and molecules and their basic structure)

- dark matter, dark energy, baryonic matter

- electrons, atoms, ions

- molecules (introduction to proteins, amino acids, enzymes)

- covalent bonds and life (thermostability)

- van der Waals interactions and life

- interaction between matter and light

4. Molecular structure of life (the basic elements required by life are carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur)

- proteins, nucleic acids, carbohydrates, lipids

- water as a solvent of life

- alternative solvents

5. Cellular structure of life (different cells found in life on Earth)

- types and structures of cells

- transcription: DNA to RNA

- translation: RNA to protein

- DNA replication

- plasmids

- eukaryotic cells

- reproduction of cells

- movement and communication in prokaryotes

6. Viruses: their role in natural environment and origin of life on Earth

7. Fungi: how they make our worlds

8. Energy for life (different types of energy acquisition in organisms: chemo- versus phototrophic forms of energy acquisition; chemiosmosis, electron transport; ATP)

- evolution of photosynthesis

- global biogeochemical cycles

- microbial mats

- thermodynamics of energy acquisition of life

9. Life in extreme environments and the limits of life

10. The tree of life (phylogenetic trees, RNA, LUCA)

11. The Universe, the Solar System and the elements of life (how stars and planets form)

12. Carbon molecules in space (organic molecules)

13. The first billion years of Earth (hypotheses about the formation of Earth, its early oceans and atmosphere; environmental conditions in which life might have emerged)

14. The origin of life (panspermia, the RNA world, early cells, hydrothermal vents, impact craters, volcanic environments, deep subsurface)

- methods used to investigate life

- stromatolites

- biomarkers and contamination

15. The rise of oxygen (major source and sinks of oxygen on Earth, Snowball Earth)

16. Mass extinctions (five major mass extinctions in the Phanerozoic, purported causes of mass extinctions)

17. Habitability of planetary bodies (habitable/Goldilocks zone and its limitations)

18. The astrogeobiology of Mars (missions, evidence for water, limits to life)

19. Ocean worlds and icy moons (astrogeobiology of moons; the evidence for water bodies under the surfaces of Europa, Ganymede and Enceladus; carbon cycle on Titan; habitability in the interior of moons)

20. Exoplanets and the search for life (methods used to detect exoplanets, diversity of exoplanets)

21. Hayabusa missions to Ryugu and Bennu (carbonaceous asteroids thought to be the rocky building blocks of the early solar system)

Practical, 60h

The practical course in astrogeobiology consists of independent work or work in groups with organic solvents, chemical reagents and cultures of bacteria and fungi. Students learn about possible contamination of ancient sedimentary and extraterrestrial samples and extraction techniques of organic matter from Precambrian sedimentary rocks and samples collected from the Moon, Mars, etc. Students study rock colonizing bacteria examining samples collected from cold and hot deserts (examination includes microscopic analyses, isolation and cultivation of microorganisms). Analysis of cultured cyanobacteria, other bacteria and fungi under epifluorescence microscope (using blue, green and UV-filters and fluorescing pigments).

Students perform ecophysiological experiments with extremophilic taxa of cyanobacteria in variable conditions to understand the importance of various ecophysiological traits in colonization of inhospitable environment.

In addition, students learn how to extract and isolate DNA from sediments, rocks, and cultured microorganisms, followed by analysis of marker genes responsible for particular processes (for example nitrogen fixation, photosynthesis-related genes) using PCR technique.

Beech, M., Seckbach, J., Gordon, R., 2021. Terraforming Mars. Astrobiology Perspectives on Life in the Universe, 1st edition, Wiley-Scrivener.

Cockell, C.S., 2020. Understanding life in the Universe.2nd edition, Wiley-Blackwell

Kolb, V.M., 2021. Handbook of astrobiology. 1st edition, CRC Press.

Rothery, D.A., Gilmour, I., Sephton, M.A., 2018. An introduction to astrobiology. 3rd edition, Cambridge University Press.

Articles in Astrobiology, Geobiology, International Journal of Astrobiology

The examination requirements cover the scope of material presented at the lectures and the practical course. The exam is in writing and includes a test and descriptive part.

Additional presentation of selected topics based on experiments and literature.